Notes:Where possible, OGJ uses data from its surveys and
published official estimates. Most reserves estimates come from governments,
which control most reserves. Government reserves estimates frequently are
influenced by geopolitical pressures. Two big reserves increases this year are
from countries where geopolitical controversy is routine: Iran and Venezuela.
Having moved large volumes of extra-heavy crude oil into the reserves
classification in recent years, Venezuela claims 298 billion bbl. Iran has
raised its reserves estimate to 154.6 billion bbl. For Russia, which doesn't
disclose country reserves, estimates vary greatly. OGJ has been conservative in
its estimates for Russia but this year increases its estimate by one-third for
the world's top producing country to 80 billion bbl. Although many giant
Russian fields are mature, the country is considered underexplored,
underdeveloped, and amenable to improved production efficiency with the growing
application of modern technology. Moreover, a push into the Russian Arctic
offshore is set to begin. For the US, OGJ relies on what had been annual
reserves estimates by the Energy Information Administration. Because of budget
cuts, however, EIA hasn't updated its reserves estimates … . The estimate here
therefore is unchanged. For China, where exploration is
active on a number of fronts, the oil reserves estimate is up about 5 billion
bbl at 25.6 billion bbl. Please read "Global
oil production up in 2012 as reserves estimates rise again,"OGJ, Dec. 3, 2012.
Proved/proven oil reserves - Generally taken to be those quantities that
geological and engineering information indicates with reasonable certainty can
be recovered in the future from known reservoirs under existing economic and
operating conditions.